Generally, with the advancements being made in mobile communication technology, mobile devices such as portable computers, mobile phones, tablets, phablets, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy consumer demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area which includes mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area which includes mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
According to some research reports, researchers predict that the next generation of mobile devices will be “wearable devices”. For example, wireless communication may be applied to watches, glasses, and even any carry supplies in the future. However, wearable devices, for example, do not have a large enough space to accommodate antennas for wireless communication. Accordingly, this has become a critical challenge for antenna designers.
It is therefore desired to provide antenna structures that are effective in smaller spaces.